Adult tennis racket head size midsize racket head size 645 cm head size inches 100 sq in stringing 16 x 19 16 x 16 type of racket tournament racket playing properties control balance 340 mm recommended height from 155 cm weight unstrung 270 g racket balance even grip size l0 l5 shape oval frame profile min 23 mm frame max 26 mm length 685 cm length inches 27 technologies head graphenext head asp adaptive string pattern seas